1. Technical Field
This invention relates generally to the transportation industry, and more particularly to a vehicle-mounted, container-lifting apparatus for loading a container onto a truck, trailer, or other vehicle, and thereafter supporting the container in transit and unloading it when desired.
2. Description of Related Art
A “vehicle-mounted container lift” herein is a lifting apparatus mounted on a truck, trailer, or other such wheeled vehicle for over-the-road use. It functions as means for loading and unloading a container onto and from the vehicle. Such a lifting apparatus may, for example, include container-engaging components powered by operator-controlled hydraulics suitable for loading containers weighing up to about four to five tons (e.g., an eight-by-eight by sixteen-foot long storage box). The container size, vehicle size, and various vehicle-related laws and regulations combine with operational, manufacturing, and cost considerations to affect the precise way in which such a vehicle-mounted container lift is configured.
U.S. Pat. No. 6,071,062 describes an apparatus for lifting, handling, and transporting a container on a vehicle that includes a carrier frame on wheels. An operator can deploy and retract the carrier frame hydraulically to and from the vehicle platform while expanding and contracting it transversely in order to clear the vehicle and engage the container. With the wheels deployed and the carrier frame engaging the container, the carrier frame hydraulically lifts the container and then wheels the container on the surface supporting the vehicle until the container is in position over the vehicle platform. The container is thereafter lowered onto the vehicle platform and the wheels of the apparatus are retracted for transport.
U.S. Patent Publication No. 2007/0071586 describes a system for loading, handling, and transporting containers on a truck that uses relatively short left and right container-engaging beams called “cradle assemblies” for holding opposite sides of a container. A hydraulically powered dolly mounted moveably on the truck includes crane-like “yoke arms” that extend rearwardly from the dolly on left and right sides of the truck to distal ends of the yoke arms on which the cradle assemblies are mounted rotatably. The yoke arms lift the cradle assemblies while hydraulic components rotate the cradle assemblies on the distal ends of the yoke arms in order to keep the cradle assemblies and the container level.
Although the above vehicle-mounted container lifts provide hydraulically powered lifting designed to keep the container somewhat level as it is loaded and unloaded from the vehicle, there are various drawbacks that need to be overcome. Thus, a need exists for a better vehicle-mounted container-lifting apparatus